Engine starter gearing



Feb. 12, 1946. E. E. HOOD ENGINE STARTER GEARING Filed June 22, 1944INVENTOR.

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Patented Feb. 12, 1946 UNITED STATES PATENT OFFICE 2,394,69lt i ENGINE,STARTER: GEARJNG Edwin Elliott Hood, Elmira, N. Y;,,..as signor toBendix'Aivi'ation Corporation south Bend, In a corporation of Delaware-1 j Application June; 22, 1944, .S eriat No. 5,41 ,525.

6 Claims.

The present invention relates to engine starter gearing and moreparticularly to a. drive. of the automatically engaging type which is;arranged to maintain the gears meshed until the engine is reliably:self-operative.

It, is; an. object; of the present invention to; provide novelenginestarter gearing in. which. a: motor driven; pinion is positively held inmesh with an engine gear while being permitted to: over-- run thestarting motor when the engine fires;

It; is' another object to provide such a. device including; a yielding:connection comprising a block: of elastically deformable material.

It is a further object: to. provide; such a. device in which the;holding means: comprises a spring pressed latch. and means. are providedfor releasing the latch when the engine is reliably self-operative.

Another object: is to provide such a device. in which the. latch is.soqformed that it cannot. project unduly or becomev disengaged from the,drive by centrifugal force or other effects.

Further objects and advantages will be apparent from the following.description, taken in connection with the: accompanying drawing inwhich: V

Fig. 1- is a. side elevation partly in section of an engine starterdrive forming a preferred. embodiment of, the invention;

- Fig. 2'- is a. section taken substantially on line. 22 of Fig. 1;

Fig. 3 is. a view similar to; Fig; 1-. showin the parts in crankingposition;

Fig. 4. is a detail in. perspective of the annular latch member, and

Fig. 5 is. a. section taken substantially on; line 5-5 of Fig. 3.

In Fig. 1 of the drawing there is illustrated a power shaft I having asmooth reduced extension 7., a shoulder 3 being formed by thereduction'.in diameter. A screw shaft 4, is. fixed in any suitable manner as bymeans. of; a cross-pin 5 on the extension 2 of the: power shaft. Apinion 6 is slidably journalled on said extension 2 between the end ofthe screw shaft and the shoulder 3 for movement into and out of meshwith a member such as a gear I of an engine to be started. Preferably,thrust washers 8 are seated against the shoulder 3 to form a stop forthe pinion in its meshing position.

A flanged nut 9 is threaded on the screw shaft 4, and means are providedfor connecting the nut to the pinion 6 for longitudinal and rotarymovement. As here shown this means comprises a barrel member Hsurrounding the nut and having an internal; flange I12; preventin g essoi the nut from thebarrel.v A. cylindrical block it; offelasticallydeiormable: material such. as. rub, her is; seated at one end; on, the:nut 9. within the barrel Hi and at: its other end; bears; against, aflanged thihrble. M which cooperates with-the nut 9.- to. form a.closed: cham r. for the rubber block- A. driving clutch. member i5 ismounted in the. open" end of the barrelv M. and is: provided with teethI56 adapted to; cooperate with teeth [1" of: a. driven. clutch. memberl8. fixed as: indicatect at In on the. pinion. 6.. Means for yieldablyholding the clutch members in engagement are provided in, the form of. adished; prin m ber 2 hearing against the driveni clutch mem ber m andretained by a thimble, 22. thimble M2, driving: clutch member l5, andthimble 2-2. are all retained inthe, end of. the barrel. II in anysuitable manner as. by spinning over the end of the barrel as indicatedat 23:. Th thimble I4 is preferablyconnected positively with; the. driving clutch member I51 by brazing or welding or in' any other suitable;manner.

Means; are provided for holding the pinion. 6 in mesh with the engine.gear I; until the aotu: ation of a releasing means by the. operator.here shown this is accomplished by means of. an annular latch member- Zlwhich slidably mounted on the flange of the. nutv 3,. being 36: tainedthereon by means ofrivets: or: studs. 2.5, 26, 2! fixed in the nut. andtraversin parallel slots: 28', 29 and 31:, in the latch memben.

Means for urging the latch eccentriloally into engagement with the screwshaft. are provided in the form of springs '30 located in slots; 28',2-9. bearing against the rivets: 25, 216.. Retaining means for thelatchis provided in the formv of. a locking ring '32having slots: 33-,34; and; 3:5 for receiving the studs 25, 2S and 21 and being sufliciently flexible to be snapped under the headsof said rivets. f v

The latching member 24 is provided interiorly with a shoulder 36,-arranged to engage. in a re.- cess 7 31 iii-"the screw shaft byeccentric movement of the latch member when in registry there: with. Therecess 31 is so located that when the latch engagestherewith, the pinionis prevented from moving back toward idle position more than thedistance necessary to release the clutch members l5, l8.

A sleeve 38 is mounted telescopically on the latch ring 24 and ispressed against the end of the barrel I I by means of a spring 39. Thesleeve 38 has a diameter'at least as great as the barrel ll so that whenthe latch has moved eccentrically to engage the screw shaft, the sleeve38 projects to that extent beyond the surface of the barrel.

A trip member 4| is mounted adjacent the position assumed by the sleeve38 when the pinion 6 is meshed with the engine gear. The trip isarranged to be slidable radially into engagement with thesleeve 38 underthe control of the operator whereby the sleeve, and consequently thelatch 24 may be moved into concentric relation with the drive thusreleasing the latch and permitting the pinion to return to idleposition. The

trip 4| may be actuated manually by the operator or may be actuatedautomatically in the man ner shown in the patent to Kearney 2,339,486.

In operation, starting with the parts in the positions illustrated inFig.1 energization of the armature shaft causes the nut 9, barrel II andpinion 6 with their associated parts to be moved to the right until thepinion meshes with the engine gear 1, the meshing position being definedby engagement of the pinion with the thrust washers 8. Further movementof the nut is resisted by the rubber block l3 which transmits itspressure and torque to the pinion 6 through the clutch members l5, l8,such transmission being cushioned by the resiliency of the rubber. Bythe time sufficient torque has be'enbuilt up to start rotation of theengine, the nut 9 has advanced within the barrel to the positionillustrated in Fig. 3 carrying with .it the latch member 24, whichmovement is permitted by compression of the spring 39.

When the engine fires, the torque on the drive is relieved, thuspermitting the nut to be moved back to the end of the barrel by theexpansion of the rubber block I3. At this time, the shoulder 36 of thelatch is moved into engagement with the recess 31 inthe screw shaft bythe action of the springs 30. After the nut 9 has moved toward idleposition suificiently to release clutch members 5, 8 further backwardmovement is prevented by the latch, so that the pinion'is retained inmesh with the engine gear while being permitted to overrun freely bydisconnection of the clutch members; ,If the engine fails to con tinueoperative, cranking is immediately resumed as soon as the speed of thestarting motor equals that of the pinion. When the engine has becomereliably self-operative the starting motor which actuates the powershaft is deenergized by the operator and trip 4| is advanced intoengagement with the sleeve 38 which is thus brought into concentricitywith the drive, releasing the engagement of the latch 24 with the screwshaft 4. The nut is then free to overrun the screw shaft andconsequently return to idle position, drawing the pinion out of meshwith the engine gear.

Although but one embodiment of the invention has been shown anddescribed in detail, it will be understood that other embodiments are.possible and various changes may be made in the form and arrangement ofthe parts without departing from the spirit of the invention asdefinedin the claims appended hereto. 7

What is claimed is:

1. In an engine starter drive a power shaft, a screw shaft fixedthereon, a pinion slidably journalled on the power shaft for movementinto and out of mesh with a gear of an engine to be started, a nut onthe screw shaft, means including an over-running clutch connecting thenut to the pinion for rotation and longitudinal movement therewith, acircular latch surrounding the screw shaft and cooperating therewithwhen moved eccentrically thereto to hold the pinion in mesh, and meansfor moving the latch co-axially with the screw shaft to release thepinion and permit it to return to idle position.

2. An engine starter drive as set forth in claim 1 in which the meansfor connecting the nut to the pinion includes a barrel member, and themeans'for moving the latch includes a sleeve in telescopic relation tothe latch and having an outside diameter at least as great as that ofthe barrel.

3. In an engine starter drive a screw shaft, a nut threaded thereon, apinion connected there with for longitudinal movement into and out ofmesh with a gear of an engine to be started and for rotary movement todrive the engine gear, an annular latch member loosely surrounding thescrew shaft and connected to rotate with the nut, said latch member andscrew shaft having means adapted to cooperate upon eccentric movement ofthe latch member to prevent movement of the nut in a direction tode-mesh the pinion and yielding means urging the latch member into itsaeccentric locking position, and releasing means for moving thelatchmember into concentric relation with the screw shaft to disconnect thelatch.

4. An engine starter drive as set forth in claim 3 in which thereleasing means includes a sleeve in telescopic relation with the latchmember, and a trip member adapted to engage the sleeve during rotationthereof and-move it into con centricity with the screwshaft. 5. In anengine starter drive, a power shaft having a fixed abutment thereon, ascrew shaft fixed on the power shaft, a nut threaded on the screw shaft,a pinion journalled on the power shaft and slidable thereon intoengagement with said abutment, means for connecting the nut and pinionincluding a block of elastically deformable material and a barrel membersurrounding the nut and block, a circular latch member surrounding thescrew shaft slidably mounted on the nut, means normally urging the latchmember eccentrically to engage the screw shaft and hold the pinion inmesh, and means for centering the latch member to release the pinion.-

6. An engine starter drive as set forth in claim 5 in which thereleasing means includes a sleeve in telescopic relation to the latchmember having a diameter at least as great as that of the barrel, andyielding means' for holding the sleeve against the endof the barrel.

E. ELLIOTT HOOD.

